A common problem in modern laundry processes is that colored fabrics when added to a laundry bath tend to release dyes into the bath. These released dyes are solubilized or suspended in the bath. The dyes may then deposit onto a different fabric or to an undesired location on the same fabric in the bath. By "bath" we mean the aqueous solution which includes water, fabric, and other chemical additives used for such purposes as cleaning and softening the fabric. A difficulty in preventing dye transfer is that one additive that will prevent the transfer of certain dyes may not prevent the transfer of other dyes that are used to color fabric.
Common fabric dyes are classified in the Colour Index, Volumes 1 to 5, third edition, published by the Society of Dyers and Colourists, Yorkshire, England and the American Association of Textile Chemists and Colourists, Research Triangle Park, North Carolina, 1971. Generally, the dyes will be classified in one of the following categories: direct, acid, disperse, reactive, basic, and vat. For example, Chicago Sky Blue is a dye for coloring fabric blue and is classified in the Colour Index as a direct dye and has the name Direct Blue Number 1. However, the dyes can also be classified by whether the dye in an aqueous solution is cationic, anionic, nonionic, or amphoteric. For example, dyes belonging to the direct, reactive, and acid dye categories, are generally anionic in an aqueous solution; and dyes belonging to the basic dye category are generally cationic in an aqueous solution. Finally, dyes classified as vat and disperse dyes are generally nonionic in an aqueous solution, but can be anionic or cationic depending on the dye and the pH of the bath. Consequently, the difficult problem in preventing dye transfer between fabrics has been to identify compounds or formulations which will inhibit the transfer of all these different types of dyes in a laundry process or at least inhibit the dyes that give the most dye transfer problems in the bath. By a "laundry process" we mean to include both household and industrial laundry processes performed at the different wash conditions which are typical worldwide.
The problem of dye transfer in laundry process is further complicated by the different types of fabrics that can be washed. For example, dyes are more likely to desorb from cotton than synthetic fabrics, such as polyester, nylon, and acrylic leading to the possiblity of more dye transfer in the bath containing higher levels of cotton fabric. However, synthetic fabrics such as polyester, nylon, or acrylics also release and attract dyes in the bath. Another problem related to fabrics is that a fabric washed zero or only a few times is more likely to release dye, requiring a prudent person to wash that fabric separately at least for the first few times.
Another problem in finding additives useful for inhibiting the transfer of dye is that some agents that are useful for inhibiting dye transfer are either incompatible with other required ingredients in a laundry formulation, would hinder the cleaning performance of the laundry formulation, or would fade the fabric. For example, organic quaternary ammonium salts are known to be useful for inhibiting the transfer of certain dyes, but are either incompatible with anionic surfactants or hinder their cleaning performance in a laundry detergent formulation. Other known compounds for inhibiting dye transfer are chlorine based bleaches. However, these compounds fade the color of the fabric.
Known compounds for preventing the transfer of dye between fabrics, include polymers of vinylpyrrolidone and vinylimidazoles (H. U. Jager and W. Denzinger, Wirkungsweise von Polymeren mit farbubertragungsinhibierenden Eigenschaften, Tenside Surf. Det. 28 (1991) 6, p. 428).
DE 3124210 A1 discloses a liquid detergent formulation useful for preventing dye transfer between fabrics washed together. This detergent formulation contains a nonionic or zwitterionic surfactant and one or more synthetic water soluble polymers selected from the following types: a polyacrylamide or a polyacrylamide partially hydrolyzed with a molecular weight over several 1,000,000; a polyethyleneimine; a polyamine; and a polyamineamide. However, DE 3124210 A1 does not address the problem of the transfer of different dye types in liquid detergent compositions. DE 3124210 A1 shows the effectiveness of the liquid detergent only against one type of dye, Sirius Bright Red F 4 BL. Furthermore, the disclosure in DE 3124210 A1 is limited by requiring that a nonionic or zwitterionic surfactant be present in the liquid detergent formulation with the polymer. This limitation may be exemplified by one who might desire to add an additive for inhibiting the transfer of dye into a detergent formulation which requires a different type of surfactant or into a fabric softener formulation.
Accordingly, one aspect of this invention is to provide compounds and compositions, that are useful for preventing all the different types of dyes commonly used in dyeing fabric, from transferring between the same or different fabric in the laundry bath. The compounds and compositions of such an invention should also be effective in preventing dye transfer with the most troublesome fabrics such as cotton.
Another aspect of this invention is to provide dye transfer inhibiting agents that will be compatible with and effective in various types of household and industrial laundry formulations.
Another aspect of this invention is to provide a process for inhibiting the transfer of dye in laundry processes using dye transfer inhibiting agents.